Reduce Airport Emissions by Eliminating Airplane Taxiing under Jet Power

Assumptions

• Eliminating taxiing under jet power would save 530 kilograms, or 0.53 metric tons of CO2 emissions per flight.
• There are 189,750 flights per year out of San Francisco International Airport

Analysis

Alternative propulsion technology has the potential to eliminate the fuel now wasted on taxiing jet aircraft, reducing pollution including CO2 emissions. In theory, this technology could save airlines enough in fuel and maintenance costs to justify its adoption on cost grounds alone. However, the technology is still in development. San Francisco has little control over the development of this technology, however, it could facilitate test runs at San Francisco International Airport, or lobby for federal regulation.

What we do now
Jet aircraft typically use their engines to power aircraft during taxiing, in preparation for takeoff and after landing. The useof jet engines in this manner wastes fuel, creating unnecessary CO2 emissions and other pollution. An estimated 189,750 flights take off or land at San Francisco International Airport each year.¹ At .53 metric tons per flight, taxiing alone accounts for an estimated 100,568 metric tons of CO2 emissions each year.

What we could do

Airlines such as Virgin and Delta are investigating the potential for using other propulsion technology during taxiing. For example, company called Wheeltug, which is in a development agreement with Delta, has patented a device that can be built into the hub of an airplane wheel, giving aircraft mobility without use of turbines or external tugs. The company estimates that this alternative technology could save 530 kilograms of CO2 emissions per flight.² Similarly, Virgin Airlines has committed to test cutting aircraft emissions by towing planes to takeoff areas at Heathrow and Gatwick. This technology is still in testing phases. However, public-private partnerships or regulatory steps by the airport could speed its adoption.

Cost
This technology is still in its development stage. In theory, once developed it could produce cost savings for airlines without added public cost. Wheeltug estimates that the annual value of cost savings that could be realized by installing its system on one Boeing 300/700 is $452,000. This does not include the capital cost of the system, which is not yet commercially available.

Carbon savings potentialIf a change in taxiing practice or technology were able to reduce emissions per flight by 530 kilograms, the total annual emissions reduction for SFO’s 189,750 annual flights would be 100,568 metric tons. This technology is still in development, so the precise impact is not known at this time.

Endnotes
¹ Airports Council International. www.aci.aero/cda/aci_common/display/main/aci_content07_c.jsp?zn=aci
² www.wheeltug.gi